Checking means for wayside train control inductors



Nov. 11, 1952 Clll CHANG CHU CHECKING MEANS FOR WAYSIDE TRAIN CONTROLINDUCTORS Filed May 2'7, 1950 in Haw xi aw kswwsww RSNEBE 1 1 m m w NRSE5% km MM 3 w fl fin am INVENTOR. C1! CIzany Ubu y Z:

HIS ATTORNEY I Patented Nov. 11, 1952 CHECKING S FOR WAYS'IDE TRAINCONTROL ,INDUGTORS Chi Chang Chuj, Pittsburgh, Pa,, assignor to-Westinghouse AirLBrake Gompany; a' corporation of PennsylvaniaApplicationv May 27, 1950,.SeriaLNo. 164,685.

'13 Claims. 1

My invention relates. to automatic trainv controllsystem. of.theintermittent inductive type, and? particularly to meansfor checkingthe wayside. inductors iemplfoyednin such systems to insure that theinductor is in proper condition to cooperate with the.train-carriedapparatus.

'Tiain control systems of. this. type have inductorslooat'ed at theentrance of each track section. 'Eachrindjuctor has a Lie-shaped. core:having a winding. thereon. and. the inductors cooper.- ate withtrain-carried equipment so that if at the time the train passes over aninductor the circuit of'the winding isopen, or if current is flowing'ina given direction through the inductor winding,..the train-carriedequipment will operate to applyithebrakes, while if at the time thetrain passes. over. the inductor the winding of the inductor :isshortci'r-cui'ted, or if current is flowingi'nthe opposite directionthrough'the inductor Winding, the train-carried equipment is notaffected;

I'thas previously beenproposed to check the integrity of. the waysideinductor by providing a relay connected in series with, the inductorwinding so that. if the. inductor is damaged or remove.d,.orthecircuitotherwise opened; the series checking, relay will. he released,-and; govern the associated signal-nor a signal inv the. rear;eitheinductor location to indicatev that the apparatus is ;not.. in. itsproper condition. Howeveri it is' also necessary to check that thewinding-of the:

inductor. does not become-short.circuited,. except by operation of. thecontrolling relays, since a short circuit inthe winding itself or-inthe-com necting wires might resultinthe erroneousoperation of. thetrain-carried apparatus, so that with the associated wayside signaldisplaying;- a

restrictive indication, the train-carriediallparatus.

would. not be. operated to apply thehrakes.

Accordingly, ,it is-an object. of. invention to provide checking meansfor train oontrol ;inductors and. which means will detect whether. theinductoris improperly open or shortcircui-ted.

Another object of my invention is .to provide checking means fortraincontrol inductors-which.-

will. detect an improperly open or shortrcircuited;

inductor, and which means providesior supply-.

ingenergy through the inductor winding in. such directionas tofurther-increase or decrease the fiuxinthe train-carriedapparatusytofurtherinmeans is arrangedso thatyundersomeconditions,V

the inductor is checked, for an open-circuiteid winding, under otherconditions the 'ihductoris checked for a short-circuitcd' winding andunder still other conditions theinductor is checked for either anopen-circuited winding, or a short-circuited winding.

Another object. ofmy invention. is, .tov provide. checking, means fortrain control ihductors,.,i'n which a low impedance path is provided forthe alternating current energy induced in the ind'uc: tor by thepassageiof the traincarriediapparatus;,. but a relatively highresistance pathi's. provided for theidirec't currentenergy employed inchecking the condition of the winding, so that the in d'uctor appearsshort-ci'rcuitedi insofar as the train-carried apparatus is concerned.

Other objects of my invention and features of'novelty thereof will beapparent from therfollowing description, takenin connection withjtheaccompanying drawing.

In. practicing my invention, I provide a. first. auxiliary relay;vhaving va winding of relatively low resistance, which may be governed.by the. control relays for the associated wayside signal; so that thewinding. of the first auxiliary relayis connected i'nseri'es withthewindingofthe inductor .at' times to. thereby detect an open circuitfailure of the inductor A second auxiliary,relay,.. having a winding ofrelatively high resistance is. provided, and may be adapted to begoverned bythe signal controlrelays in suchmanner that the winding ofthe secondauxiliary relay is connected across the inductorvwinding, attimes, in which case the second auxiliary relay is released .if theinductor winding is short circuit'ed; The circuits may be arranged so.that either the short circuit check". or the open circuit checker bothare applied as determined by the signal control relay which governs theassociatedwayside signal; In, order'to provide an equivalentshortcircuitedine ductor for the train-carried. apparatus, a con:-denser is connected across the inductor winding at times, to therebyofier a low impedan-ce pathr for the energyinduced in the inductorwindingeby the passage of the train-carried apparatus. Ad-

ditionally, the direct current energy which is passed through theinductor winding for checking purposes is arranged to flow in the properdirection to assist in properly influencing the traincarried apparatus.The checking relays may govern additional trafiic governing means in therear of the inductor, to warn an approaching train that the inductor isnot in proper condition.

I shall describe one form of checking means for train control inductor,which means is a preferred embodiment of my invention, and shall thenpoint out the novel features thereof in claims.

The single accompanying drawing is a diagrammatic view showing a stretchof railway equipped with signals for governing movements of trafiic inone direction only, and having train control inductors for the controlof trains moving through the stretch. It is to be understood that myinvention may also be employed in connection with train control systemson single track railways where trafi'ic moves over the stretch in eitherdirection, by providing similar a aratus for the inductors governing thetraflic movements in the opposite direction.

Referring to the drawing, the reference characters I and 2 designate thetrack rails of a sectionof railway track, over which tra-fiic moves inthe direction indicated by the arrow, that is, from left to right. Thestretch is divided into sections such as section 2T, each of which hasassociated therewith a wayside signal, such as signal 2S, here shown asbeing of the well known color-flight type,, for governing the entranceof trafiic into the correspondingly designated track section. Thesewayside signals are governed by the occupancy of the first and thesecond sections in advance of the signal to provide a conventionaltwo-block, three indication signaling system That is, when the firsttrack section in advance of a signal is occupied by a train, the signalwill display a red aspect, indicating stop; when the first track sectionin advance is unoccupied' and the second track section in advance of asignal is occupied, the signal will display a yellow aspect, indicatingapproach next signal prepared to stop; and when the first and secondsections in advance of the signal are unoccupied,

the signal will display a .green aspect indicatin "clear." Each of thetrack sections is provided with a conventional direct current trackcircuit, including a track battery, such as battery ITB, connectedacross the rails at the exit end of the section, and a track relay, suchas relay ITR, connected across the rails at the entrance end of thesection, in order to detect the occupancy of the section by a train.Each of the signals has associated therewith a signal control relay suchas relay ZHDR, which governs the associated signal in accordance withthe occupancy of the track sections in advance of the signal.

Adjacent the entrance end of each track section, there is provided atrackway inductor designated by the reference character V preceded by,the numer of the track section with which the inductor is associated,for example, inductor 2V located at the entrance end of section 2T. Eachinductor, as shown, comprises a ,core carrying a winding, and is adaptedto cooperate with traincarriedapparatus in such a manner that anautomatic application of the brakes occurs or a stop indication is givenon a train passing an inductor which is effectively open circuited, butno effect is produced on a passing train when the inductor iseffectively short-circuited. More-- 4 over, if a direct current ispassed through the inductor winding in one direction or the other, itwill tend to increase or decrease the efiect upon the train equipment,so that if the inductor is effectively open circuited insofar as theenergy induced therein by the passage of the train equipment isconcerned, and in addition, direct current energy is flowing in a givendirection through the inductor winding, the effect upon thetrain-carried apparatus is increased over that produced by an inductorwhich is eifectively open circuited but does not have direct currentflowing in its winding. A similar condition is found in the case of aninductor which is effectively short circuited insofar as the energyinduced therein by the passage of the train equipment is concerned andhas a direct current flowing therethrough in the opposite direction tothat in which it flows when the inductor is effectively open circuited.

The train-carried apparatus is not illustrated because it forms no partof my invention, but it may be, for example, of the type shown anddescribed in Letters Patent of the United States No. 1,698,470, grantedto Paul N. Bossart on January 8, 1929.

Each of the inductors is provided with means for checking the integrityof the inductor, comprising a first auxiliary relay, such as relayZHDPR, and a second auxiliary relay such as relay ZCKR. The circuits forgoverning these relays and the associated inductor and the circuits forsupplying energy to the signal lamps are shown in detail for signal 28,but it will be understood that similar equipment is provided for each ofthe other signals and inductors in the stretch.

At each of the signal locations, energy for the operation of the variousrelays and signal lamps is provided from a suitable source of directcurrent, such as the battery LB shown, the positive and negativeterminals of which are designatedv by the reference characters B and N,respectively.

The operation of the circuits associated with signal 28 under variousconditions will now be,

described, and it will be seen that the circuits associated with theother signals in the stretch will operate in a similar manner.

The apparatus is shown in the normal condition, that is, the conditionit assumes when there is no train occupying any section in the stretch.

At this time the winding of signal control relay ZHDR is supplied withenergy by a circuit which may be traced from terminal B at signal,location 3S, over front contact a of relay 3HDPR,

front contact a of relay 2TB, through the winding of relay 2HDR fromleft to right, front contact b of relay 2TB, and front contact b ofrelay SHDPR to terminal N. Relay ZHDR is of the polarized type, havingneutral contacts which are picked up when energy flows through thewinding of the relay in either direction and are released when no energyis supplied to the wind-' ing of the relay, and also having polarcontacts which are operated from a normal to a reverse position whenenergy is supplied through the winding of the relay in one direction,and are operated to their normal or left-hand position when the windingof the relay is supplied with energy of the opposite polarity. The relayis constructed and arranged so that with energy flowing through thewinding from left to right, the polar contacts of the relay will beoperated to their left-hand or normal position, and the neutral contactswill be picked up. Thefirst at tthis-itimeby a circuit which may betraced from: terminal B at .front. contact. a" of. .relay 2HDR, overnormal contact 12 of relay 2HDR,.

back. contact a of. thesecon'd'auxiliary relay ZCKR, through: the.winding of relay ZHDPR fromtright to left,.front contact-.d of relay2HDR,.

through the windinguof. inductor 237 from right. to sleft,=. and backcontact d .of; relay ZCKR' "to terminal N. .Accordingly, relay 2I-IDPRwill :have:

its-i contacts :picked up at this time.v A circuit.

for supplying: energy to the green lamp G of signal 28 may betraced'froml terminal Bat-front contact rd of. relay AHDPR, over normalcontact I of relay -2HDR,.. andthrough the greenilamp G ofxisig'n'al 2Sto terminal N. Accordingly, signal 2S-will. displayagreen aspect,indicating. fclearf Underathe normal condition, the relay |HDR.,. whichgoverns signal IS, in the rear: of signal 28, in a similar manner tothat in which relay 2HDRgoyerns signals 2S,.is supplied with energyby'aacircuit which may. be traced from terminal Bwatiront. contact b ofrelay ZHDPR, over front contact a; of relay 'ITR, through the winding ofrelay. l-HDR from left, to right, front contact I) of relay ITR, andfront contact'c of relay ZHDPRto terminal N. Thus, it will be seen thatrelay IHDR, which is similar in construction ando'peration to relay2HDR,will have its neutral contactspicked up, and its p01arc0ntacts willoccupy-their normal position, so thatsignal IS; will also display agreen aspect.

.From: the foregoing, it will be seen that, with no train occupying the:stretch, the signals will each display a, green aspect indicating clear.When a signal is displaying a green aspect, it is "desired that theassociated inductor such as inductor 2V will be in such condition thatif a train moves by the inductor,. the. equipment on.

the train will not be afiected so that the train may continue onthrough. the, section. Accordingly, atv this time it is necessary thatthe inductor 2V be effectively short circuited insofar as energy inducedin the inductor by the passage of the train-carried apparatus isconcerned. In order toprovide this effective short circuit condition ofthe inductor, a condenser Q, which has a relatively large capacity, isconnected across the winding of inductor 2V by front contact a of relay2HDPR and normal contact e of relay 2HDR. The capacity of condenser Q isselected so that at the lowest frequency-of energy induced inrthe.inductor 2V, which would be that produced by a train moving by theinductor at a predeterminedrelatively low speed, the reactance of thecondenser Q will be comparable to the reactance of the inductor 2V, sothat the combination .of the inductor winding and the condenser forms aresonant circuit, and thereby the effective impedance of the circuit isreduced to that represented by the resistance of the winding and thevarious connections normally. At higher speeds, the frequency will ofcourse be increased,

butthe reactance of the condenser will be lowered, so that by choice ofa condenser of suitable value, say, for example, 4000 microfarads, theimpedance may be kept relatively low for the range of train speedsinvolved. Accordingly, it will be seen that with the condenser Qconnected across itswinding the inductor 2V is effectively shortcircuited insofar as the train-carried apparatus vis concerned.Moreover, as was previously pointed out, thecircuit is arranged so thatthe direct current energy which. flows through the inductor forproviding energizatipn'v .ot

relay 2I-IDl=!mflows ithrouglt thesindiictor lnzsuch a zdirectionfithatlit prevents thezincrease .-.ofc-fiux in' astrain carried apparatus; as.the trainecarried.

apparatus -passes fthe inductor, which assists in:

preventing-operation. on the train-carried: equipment; sincethecondenserrQ isrconnectedacross. the inductor winding; at this. time, .itwill ;be

charged by the directcurrent energy to some given.value. v This chargeisautilized for: picking upxrelayfilfiKR;.as-willzbe-subsequentlydescribed.v

sin'ce under normal" conditions the signal is: is -cl'ear, and ztheiinductor- 2V should, be-short ci'rcuit'ed, it is not;necessaryto checkthe inductor winding; tor a :shortzeircuit; Accordingly; the: secondauxiliary relay, .ZCKR. is: not connectedin the. inductor: circuitatxthis time.

It 'willbevseenzfromi the" foregoing,- that; when.

theisigna'ldisplays azgreerraspect'indicating;pro-- ceed, the inductoris. checkedutor, insure itssine tegrity, andtat the:v same: timeiti-is:provided zwitha a relatively :low impedance: path. for"the=alter:-=

nating current energy induced 'insthetim'luctors.by.

the passage :of the trainecarried: 'requipment-,. sozthatshoulda: .trainpass? theinductor at this time-no :operation of the "train-carried.apparatus will take place, .It will. further be seen that, shouldtheinduc'tor 2V:.becomedisplacedfor. some reason or other by:sufficient. .amount that it-cno, longer wouldbein .a position tocooperate with. thectrain-carried: equipment, :such displacement of theinductor would likely cause abreak in'thea wires whichconnectthe-zinductor awindingwtocthe various relayw circuits,v andrtheqcircuit :for supply? ing; energytto relay 'ZHDBR: .Would'beinterruptedi and the -relay-would releases In such-casathe contact atof relay :2HDPR would interrupt the: supply of. energy to the greenlampG of signab 2S, ,and 1establish=v a circuit for. supplying. energy tothe red lamp-Ref signal .25 over back contact" d. Moreoventhecontactsbandc of relay ZHDPR' wouldreversethe polarity of the energysuppliedoverrthe line. wires to-signal'control relay II-IDR whichgoverns signal IS, so that signal IS would then; display a yellow aspectindicating ap proach, so that .a .train passing signal IS would be.prepared to; stop, at the-next. signal, inthis case; signal 28.Accordingly, itwill be seen thatwith .the apparatus :arrangedas:described, the: inductor 2V iseifectively checked against an opencircuit, or a. displacement from its proper positio n-;byasuflicient-amountto break the connectnsi:W res-.

It will now be assumedi'that aitrain, moving from left to right, passesthe inductor 2V and the signal 2S and enters section. 2T with signal 23displaying a green aspect. Whenth'e train enters section 2T, track relayZTR, will release, and its contacts a and b will interrupt the circuitfor supplying energy to the signal control relay 2HDR, and the neutralcontacts of'relay ZHDR will release. When contact. a of relay 2I-IDRreleases, the circuit previously traced for supplying energy to thefirst auxiliary relay ZHDPRis interrupted, and relay ZHDPR. willrelease. The: circuit for supplying energy to relay 2I-IDPR isadditionally interrupted byzfront contact (1 ofre-- lay ZHDR.

When relay ZHDPR. releases, its front contact a disconnects thecondenser Qfrom the inductor 2V and its back contact a establishes apick-upcircuit for supplying energy previously stored in the condenser Qto the lower winding ll of relay 2CKR. This pick-up'circuit maybe tracedfrom the right-hand plateuot' condenser Qyove'r' back-contact a0f-.relay.2I-IDPR,..and through-the winding [1 of' relay 2CKR from left.to right to the left-hand plate or element of condenser Q.

Accordingly, the energy previously stored in condenser Q when it wasconnected in the circuit for inductor 2V is now discharged through thewinding l! of relay 20KB, and the parts are proportioned and arranged sothat the value of this energy is sufficient to cause the contacts ofrelay ZCKR to pick up. When contact b of relay ZCKR picks up, 9, stickcircuit is established for supplying energy to the upperwinding l5 ofrelay ZCKR, which circuit may be traced from terminal B at back contacta of relay 2HDR., over front contact 1) of relay ZCKR, through thewinding [5 of relay ZCKR from left to right, normal contact of relayZHDR, front contact 0 of relay ZCKR, and through a reactor L to terminalN. Accordingly, the contacts of relay ZCKR. will be retained picked up,after the condenser Q has dissipated all of its charge through windingI! of relay 2CKR. Moreover, at this time, energy is supplied to thewinding of inductor 2V by a circuit which may be traced from terminal Bat front contact d of relay 20KB, through the winding of the inductor 2Vfrom left to right, over back contact d of relay 2HDR., front contact cof relay ZCKR, and through the reactor L to terminal N. It will beapparent that the winding l of relay ZCKR and the winding of inductor 2Vare effectively energized in multiple atthis time from the directcurrent source.

The resistance of the winding I5 of relay ZCKR is-selected andproportioned so that it has a rela-" tively high resistance incomparison with the resistance of the winding of inductor 2V. The partsare proportioned so that. as long as the winding of inductor 2V isintactand not short circuited, the current which flows through windingl5 of relay ZCKR is sufficient to keep the contacts of relay ZCKR.picked up. However, if the winding of inductor 2V should become shortcircuited for any reason, it will effectively shunt the winding it ofrelay 20KB, and the current flow through winding l5 of relay 20KB willbe reduced to the point where the relay will release its .contacts. Ifrelay ZCKR, becomes released due to a short circuited inductor, contactb of the relay opens the stick circuit previously traced,

so that the relay remains released. It will be seen therefore that thesecond auxiliary relay ECKi-t serves to determine whether or not thewinding of inductor 2V is short circuited when the train occupies thesection 2T.

-When signal 2S is displaying a red aspect due to the train in section2T, the inductor 2V should represent an effective open circuit for anytraincarried apparatus which may pass the inductor. The reactor L, whichis connected in series with thewinding of inductor 2V, is proportionedand arranged so that although it affords little resistance to the flowof the direct current energy through the inductor winding, it willpresent a relatively high'irnpedance to alternating current energyinduced in the inductor by the passage of train-carried equipment. Also,the winding I5 of relay 20KB, which is now connected across the windingof the inductor, presents a relatively high impedance to the alternatingcurrent energy induced in the inductor due to the passage of thetrain-carried equipment. Accordingly, insofar as the train-carriedapparatus is concerned the inductor 2V is opencircuited at this time,and should a train proceed past the inductor the train-carried apparatuswill operate to initiate an automaticflbrake application. Moreover, it

will be seen that the flow of direct current energy through the windingof inductor 2V at this time is in the opposite direction'to thatpreviously traced when signal 28 was displaying a "clear aspect. Theparts are proportioned and arranged so that the flux set up by thecurrent flow through the winding of inductor 2V at this time is such asto cause an increase in the flux in the train-carried apparatus, therebyfurther assisting in providing the proper operation of the train-carriedequipment to initiate an automatic brake application if it passes theinductor.

With the signal 28 at stop, it will be seen that it is not necessary tocheck the inductor winding for an open circuit, as relay ZHDPR isalready released due to the fact that relay 2HDR. is released, so thatthe signal IS in the rear of signal 2S is already displaying an approachaspect because signal 2S is displaying a stop aspect. I

When the train vacates section 2T and is occupying section 3T, relay 2TRwill pick up, and at this time relay SHDPR is released, so that energyof the opposite polarity is supplied to relay 2HDR. Accordingly, thepolar contacts of relay 2HDR. will be operated to their reverse positionfollowing which the neutral contacts of the relay will pick up.

It will be seen that the relay ZCKR. is retained relay ZCKR and throughthe reactor L to terminal N. Then when the neutral contacts of relay2HDR. pick up a stick circuit is completed from terminal B over frontcontact a of relay 2HDR., reverse contact 12 of relay ZHIDR, frontcontact I) to relay ZCKR, through the winding l5 from left to right,reverse contact 0 of relay 2HDR, front contact d of relay 2HDR., throughthe winding of relay ZHDPR from left to right and front contact a ofrelay ZCKR to terminal N.

At this time, the relay ZHDPR is also energized by a second circuit inmultiple with the above traced stick circuit for relay 20KB. and whichsecond circuit can be traced from terminal B at front contact 11 ofrelay ZCKR, through the winding of inductor 2V from left to right, frontcontact d of relay 2I-IDR, through the Winding of relay ZHDPR from leftto right and over front contact a of relay ZCKR to terminal N.

Accordingly, it will be seen that the second auxiliary relay ZCKR iseffectively connected-in multiple across the winding of inductor 2V, andthe winding of relay 2HDPR is effectively connected in series with thewinding of inductor 2V when the section 2T is unoccupied-and thesections, a circuit is established for supplying energy to the yellowlamp Y of signal 2S, which circuit a may be traced from terminal Batfront contact d of relay ZHDPR, over reverse polar contact I of relayZHDR, and through the yellow lamp Y of signal 2S to terminal N.Accordingly, signal 25 at this time will display a yellow aspectindicating acm ar approach the next signal prepared to stop. WithreIa-y-ZHDPR picked up, its contacts band establish a circuit forsupplying energy of normal polarity over the line wires and. contacts aand b of relay ITR to the winding of relay IHDR, so that signal IS inthe rear of signal 28 displays a green aspect indicating clear.

The winding of relay ZHDPR which is now connected in series with thewinding of the inductor 2V with the battery presents a relatively highimpedance to the alternating current energy induced in the inductor dueto the passage of a train-carried equipment. Also, as statedhereinbefore, the winding l5 of relay ZCKR, when it is connected acrossthe inductor winding presents a relatively high impedance to theener'gyinducedin the inductor by a train-carried equipment. It followsthat the inductor 2V is in effect open circuited when the signal 28displays its yellow aspect and should a train moving from left to rightpass over the inductor it will initiate an automatic brake condition onthe train. It is tobe pointed out that in train control systems ofthetype here involved the equipment is usually arranged so thatanautomatic brake application is initiated when a train passes over aninductor at an approach signal. It is to be observed that these traincontrol systems are generally provided-with means wherewith anautomatic'brake application can be forestalled by the proper operationof the apparatus on the train by the en- 'gineman.

If at this time the inductor 2V should become displaced or damaged insuch manner as to break the circuit including the inductor winding, thesupply of energy to the winding of relay ZHDPR will be interrupted andthe contacts of relay Z HDPR will be released. When contact d of relay2HDPR'releases it establishes the previously traced circuit forsupplying energy to the red lamp R of signal 28, and additionally, itscontacts b and c pole change the energy supplied to relay IHDR so thatsignal IS displays a yellow aspect. Accordingly, the inductor W atsignal location I S is placed in condition to cause an automaticapplication of the brakes of a train which passes the signal at thistime, so that the train will be stopped before reaching the damaged ordisplaced inductor. Moreover, if the inductor 2V or the wires connectingthe inductor'with the apparatus become short circuited, the resultingshort circuit will effectively shunt the supply of energy from thewinding l5 of relay ZCKR, so that relay 2CKR will release its contact.With polar contact I) of relay 2HDR in its reverse position, if contacta of relay ZCKR becomes released the supply of energy tothe winding ofrelay ZHDPR is interupted, so that the'signal 23 is governed to displaya red aspect, and the signal IS in the rear of signal 28 is governed todisplay a yellow aspect.

It will be seen, therefore, that in the event of a displaced, damaged orshort circuited inductor at any of the signal locations in the stretch,the associated signal will be governed to display a stop aspect, and thenext signal in the rear willv be governed to display a yellow aspect,and additionally, the inductor associated with the signal in the rear ofthe damaged inductor will be placed on an open circuitstatus, toinitiate the application of the brakes of a train passing the signal.

Whenthe train; inquestion clearssection 3T:in advance of signal 38, therelay J3HDPR, whichis controlled ma mannensimimrto:re1ay'i2IiDPR.

will become pickedup, thereby pole. changing the energy supplied torelay ZHDR. When the polarit-y of the energy supplied to relay 2HDR isreversed, the neutralcontacts of relay ZHDR release, the polar contactsareoperated to their normal position, and "thereafter-the neutral con.-tacts of the relay pick up again, in the well known manner of operationof polarized relays and the apparatus is restored to its normal.condition as shown in the drawing.

'When the apparatusis restored to .normal energy is supplied to thewinding of relay 2HDPR by the circuit previously traced and by whichcircuit the direction of the flow'of currentthrough the winding of relayZHDPR, is reversed from that flowing ln-the relay when the signal 28displays its yellow aspect. The reversal of directionfof current flowthrough the circuit including the winding of relay 2HDPR at this timedoes not result in the release of the contacts of relay zHDPR, sincethisrelay "is of theretained-armature type, that is, the relay isconstructed and arranged so that the-contacts do not release when thesupply of energy to the windingof the relay is reversed, provided thatsuch reversal occurs within a predetermined time interval, which-interval "is longer than the time of reversal of-the contact of-thepolarized relayZI-IDR. Accordin'ga ly, the contacts of relay 2HDPR inthe lighting control circuit for signal 2S and the pole changingcontacts in the circuit for governing relay lI-IDR of the signals in therear do not release at this time, so that the signal ZS is preventedfrom displaying a momentary red aspect --whil e theindication ischanging from yellow to green and signal IS continues to display a greenaspect. With contact 11 of relay ZHDR picked up and normal polarcontactf of relay ZHDR closed, thecircult for supplying energy to thegreen lamp G is again established, so that signal 2S again displays agreen aspect.

It will be seen from the foregoing, that I have provided checking meansfor wayside inductors of an automatic train control system, employing alow resistance relay adapted'to be connected in series with the inductorattimes, and a high resistance auxiliary relay adapted to be connectedin multiplewith the winding of the inductor at times, to thereby checkthe'inte'grityof the connections to the inductor winding, and to.continuously provide detection of ,an open circuited inductor; a shortcircuited inductor, whether caused by mechanical derangement of theinductor or its winding.,,o r a short or an opencircuit in the wiringwhich connects the inductor with the wayside relay.

Although I have herein shown and described only one form of checkingmeans for train control inductors, it is to be understoodthat variouschanges and modifications may be madetherein within the scope of. theappended claims with,- out departing from ithespiritandscope of myinvention.

Having -thus described my invention, what *I claim is:

'1- In combination with a wayside'tra-in' control inductor windingsusceptible to-open or-short circuit conditions, checking means fordetermining whether or not said inductor winding is open circuited orshort circuited, comprising a source of energy, a firstauxiliary relayhaving a glow resistance winding and a second auxiliary -rel-'ayhavinglaihigh resistance-winding,"a first tmeans for selectivelyconnectingsaidflow ance'winding of said first :auxiliaryrel-ayan'inductor winding in series across said source, a second circuit meansfor selectively connecting said high resistance winding of said secondauxiliary relay across said inductor winding, said first auxiliary relaybeing arranged and proportioned so that its contacts are released whensaid inductor winding is open circuited, and said second auxiliary relaybeing arranged and proportioned so that its contacts are released whensaid inductor winding is short circuited, and indicating means governedby said first and second auxiliary relays.

' 2. In combination, a wayside train control inductor windingsusceptible to open or short circuit conditions, checking means fordetermining whether or not said inductor winding is open circuited orshort circuited, comprising a source of direct current energy, a firstauxiliary relay having a low resistance winding and a second auxiliaryrelay having a high resistance winding, first circuit means forselectively connecting said low resistance winding of said first relayand said inductor winding in series across said source, second circuitmeans for selectively connecting said high resistance winding of saidsecond relay across'said inductor Winding, a capacitor, and means forselectively connecting said capacitor across said element foreffectively short circuiting said element with respect to alternatingcurrent.

3. In combination, a wayside train control inductor winding susceptibleto open or short circuit conditions, checking means for determiningwhether or not said inductor winding is open circuited or shortcircuited, comprising a source of direct current energy, a firstauxiliary relay having a low resistance winding and a second auxiliaryrelay having a high resistance winding, said high resistance windinghaving a high reactance, first circuit means for selectively connectingsaid low resistance winding of said first relay and said inductorwinding in series across said source, second circuit means forselectively connecting said high resistance winding of said second relayacross said element, a reactor, and means 'for selectively rendering theimpedance of said first circuit means comparatively high with respect toalternating current comprising means for selectively connecting saidreactor in series with said low resistance winding of said first relay.

4. In combination, a wayside train control inductor winding susceptibleto open or short circuit conditions, checking means for determiningwhether or not said inductor winding is open circuited or shortcircuited, comprising a source of direct current energy, a firstauxiliary relay having a low resistance winding and a second auxiliaryrelay having a high resistance winding, said high resistance windinghaving a high reactance, first circuit means for selectively connectingsaid low resistance winding of said first relay and said inductorwinding in series across said source, second circuit means forselectively connecting said high resistance winding of said second relayacross said element, means for effectively short circuiting said elementwith respect to alternating current, comprising a capacitor and circuitmeans for selectively connecting said capacitor across said element, andmeans for selectively rendering the impedance of said first circuitmeans comparatively high with respect to alternating current comprisinga reactor selectively connected in series with said low resistancewinding of said first relay.

.5. ,In combination, a train control wayside device located along astretch of railway track, a control circuit for said device, said devicebeing adapted to assume its active train-stopping condition unless saidcontrol circuit is closed to present a relatively low impedance toalternating current induced in said device, a control relay forgoverning said control circuit in accordance with traffic conditions ofsaid stretch of track in advance of said wayside device, a firstauxiliary relay having a low resistance winding, a second auxiliaryrelay having a high resistance winding, first circuit means governed bysaid control relay for selectively connecting said low resistancewinding of the first auxiliary relay in series with said controlcircuit, second circuit means governed by said control relay forselectively connecting said high resistance winding of the secondauxiliary relay in multiple with said device in said control circuit, asource of direct current energy having connections to said controlcircuit governed by said control relay, whereby said first auxiliaryrelay is energized when the control circuit for said device is not opencircuited and said second auxiliary relay is energized when the controlcircuit for said device is not short circuited, with respect to energysupplied from said source, and traffic governing means in the rear ofsaid device governed by said first and said second auxiliary relays.

6. In combination, a train control wayside device having a controlcircuit and adapted to assume an active condition unless said controlcircuit is closed to present a relatively low impedance to alternatingcurrent, a control relay for governing said control circuit, a source ofdirect current energy, a first auxiliary relay having a low resistanceWinding, a second auxiliary relay having a high resistance winding,first circuit means governed by said control relay for selectivelyconnecting said low resistance winding of the first auxiliary relay inseries with said source in said control circuit, second circuit meansgoverned by said control relay for selectively connecting said highresistance winding of the second auxiliary relay in multiple with saidsource and said device in said control circuit, and traffic governingmeans in the rear of said device governed by said first and said secondauxiliary relays.

'7. In a train control system, in combination, a wayside train controlinductor located alon a stretch of railway track having a winding andarranged to assume its inactive non-stopping condition when said Windingis efiectively short circuited with respect to alternating currentinduced in said winding, and to assume its active stopping conditionwhen said winding is effectively open circuited with respect toalternating current induced in said winding, a control circuit for saidwinding, a control relay governed by trafiic conditions in said stretchin advance of said inductor, means including said control relay foreffectively opening or closing said control circuit to effectivelyrender said winding open circuited or short circuited for alternatingcurrent induced in the winding, and checking means for determining ifsaid inductor is open circuited or short circuited, comprising a firstauxiliary relay having a winding connected in series with said inductorwinding, a second auxiliary relay having a winding connected in multiplewith said inductor winding, means including a source of direct currentenergy for energizing said first and said second auxiliary relays, andmeans governed by said first and second auxiliary relays forindiicating' he open circuited bra-short circuitedcondition 'ofsaidinductor wimiing.v

circuit -or-a short circuit, said checking means comprising a source ofdirect current, a first auxiliary relay, a second auxiliary relay, firstcircuit means governed by said control relay for connecting a winding ofsaid first auxiliary relay inseries with said winding of said device andsaid source. second circuit means governed by said control relay forconnecting a winding of said second relay across the said winding ofsaid device in multiple with said source, a condenser governed by saidcontrol relay, third circuit means for connecting said condenser acrossthe winding of said device, a reactor, fourth circuit means forconnecting said reactor in series with the winding of said device, and acircuit governed by said first and second auxiliary relays.

9. In a railway signaling system for a stretch of track comprising awayside inductive trafiic controlling device for transmitting controlinfluences to a moving vehicle under adverse traffic conditions aheadincluding a winding which if effectively short circuited by a circuithaving a low impedance to alternating current places said device in itsinactive condition, control means for said device, and traific governingmeans located in the rear of said device, the combination with theforegoin of checking means for determining if said winding is defectivedue to an open circuit or a short circuit, said checking meanscomprising a first auxiliary relay having a low resistance winding, asecond auxiliary relay having a first and a second winding, said firstwinding of said second auxiliary relay having a relatively highresistance, a source of direct current, a condenser, a reactor, firstcircuit means governed by said control means for selectively connectingsaid low resistance winding of said first auxiliary relay in series withsaid winding of said device and said source, and for connecting saidcondenser across said winding, second circuit means governed by saidcontrol means for selectively connecting said condenser to the secondwinding of said. second relay for picking up the second relay by energystored in said condenser, and for connecting said first winding of saidsecond relay in multiple with said source and the winding of said deviceby a stick circuit including in series a contact of said second relayclosed when the second relay is energized, third circuit means forselectively connecting said first relay winding in series with saidsource, said reactor and the winding of-said device and said firstwinding of said second relay in multiple with the winding of saiddevice, and circuit means governed by said control relay, said firstauxiliary relay, and said second auxiliary relay for controlling saidtrafiic governin means in the rear of said device.

10. In combination, a train control wayside inductor having a windingand adapted to assume a restrictive or non-restrictive conditionaccording as it presents in effect an open circuited or short circuitedcondition of its winding as far as alternating: current induced the:winding is concerned, a control relay operable to a firstor asecondposition to represent arestri'ctive anda "for alternating current,checking means including an-auxiliary relay and a source ofdirect-current, a second circuitincluding first position contacts ofsaid controlrelay to connect -a winding of said auxiliary relay and saidinductor winding in multiple across said direct current source, saidauxiliary relay being energized when said inductor winding is opencircuited and deenergized when said inductor winding is short circuited.

11. In combination, a train control wayside inductor having a windingand adapted to assume a restrictive or non-restrictive conditionaccording as the inductor presents a relatively high impedance or arelatively low impedance to alternating current induced in said winding,a capacitor, a direct current source, an auxiliary relay, a controlrelay, said control relay being operable to a first and a secondposition to represent a restrictive and a, non-restrictive traificcondition, respectively, a first circuit including second positioncontacts of said control relay to connect said capacitor across saidinductor winding for the inductor to present its non-restrictivecondition, a second circuit including first position contacts of saidcontrol relay to connect a winding of said auxiliary relay and saidinductor winding in multiple to said direct current source when saidinductor is disconnected from said capacitor to present its restrictivecondition, said auxiliary relay being shunted and released in responseto said inductor winding being short circuited.

12. In combination with a Wayside train con trol inductor windingsusceptible to open and short circuit conditions, checking means fordetermining whether or not said winding is open circuited or shortcircuited, comprising a source of energy, a first auxiliary relay havinga low resistance winding, a second auxiliary relay having a highresistance winding, a first circuit including in series said source ofenergy, said low resistance winding of the first auxiliary relay,

and said inductor winding, a second circuit in-' cluding in series saidsource of energy and said high resistance winding of the secondauxiliary relay and said inductor winding connected in multiple, controlrelay means, said control relay means having contacts operable todifferent positions in response to different conditions, said contactsbeing interposed in said first and said second circuits to govern theoperation thereof, and indicating means governed by said first and saidsecond auxiliary relays.

13. In a train control system having a wayside train control inductorprovided with a winding and eiiective to assume a non-stopping conditionwhen said winding is effectively short circuited with respect toalternating voltages induced therein and effective to assume a stoppingcondition when said winding is eliectively open circuited with respectto alternating voltages induced in the inductor winding, said systemhaving a control relay governed by traffic conditions and provided withcontacts operable to a first and a second position in response to afirst and a second trafiic condition respectively, and a control circuitfor said inductor winding which circuit is closed or open according assaid control .relay contacts are operated to said first or secondpositions, checking means for said wayside inductor comprising, incombination, a first and a second auxiliary relay, a source of directcurrent,

' a first checking circuit including in series said irect currentsource, a winding of said first auxiliary relay, said inductor windingand contacts of said control relay closed in their first position, tothereby check an open circuit of the inductor winding, a second checkingcircuit including in series said source of current, a winding of saidsecond auxiliary relay and said inductor winding in multiple, andcontacts of saidcontrol relay closed in their second position, tothereby check a short circuit of said inductor winding, and trafficgoverning means governed by said first and second auxiliary relays.

l CI-II CHANG CHU.

REFERENCES CITED The following references are of record in th file ofthis patent: 1

UNITED STATES PATENTS Name Date Number Thompson et a1. Dec. 20,1927

